Drilling sleeve



C. F. TERRELL, JR

DRILLING SLEEVE Filed Oct. 2, 1941 INVENTOR. Charles .Terrell J PatentedAug., 3, 1943 DRILLING SLEEVE Charles F. Terrell, Jn, Olney, Ill.,assignor to 1211c Pure Oil Company, Chicago, 111., a corporation of OhioApplication October 2, 1941, Serial No. 413,246

11 Claims.

This invention relates to drilling strings employed in the rotarydrilling of wells, and is more particularly directed to improved" bottomhole assemblies.

In order to increase the rate of penetration of the drillbit into the.formation, resort has generally been had to two methods, namely,increasing the speed oi rotation of the bit and increasing theweight onthe drill bit, so that the cutting edges of the bit bear against theformation 'with increased pressure. Greater rates of penetration can beobtained for a given speed 01 rotation when the weight on the drill bitis increased.

It is an object of this invention to provide a drilling string having ahigh proportion of the weight at the lower end thereof, and more par:

ticularly, to provide a bottom-hole assembly of increased weight.

It is another object of this-invention to provide a bottom-hole assemblyhaving increased weight distributed in such manner as to reduce failuresin the drilling string;

It is a further object of this invention to provide weighted bottom-holeassemblies in which the concentration of stresses in the joints isavoided.

It is still another object of this invention to provide a bottom-holeassembly having weighting sleeves of unusually high' flexibility mountedthereon. K

It is still another object of the invention to provide means forincreasing the rate ofpenetration-of the drill in rotary drillingoperations.

It is a further object of this invention to provide a bottom-holeassembly having flexible weighting sleeves mounted thereon which may beemployed with a minimum risk of becoming nectionssuch as l2 by tooljoints composed of. pin elements I3 and box elements l5 preferablyoflarger outside -.,diameter than the drill pipe.

of through the tool joint 2| in a conventional mariner.

Betweenv the tool joints l5 and 2| and encasing the drill pipe ll thereis mounted a loose fitting holldw cylindrical weighting sleeve 23, theinternal diameter of which is necessarily larger than that of the drillpipe II and is sufliciently large to allow for a small amount of annularfree space 25 between the sleeve and drill pipe. This annular space mayconveniently be from about 1 6 to inch, .the miniruum being that whichpermits the sleeve to fit around the drill y pipe without reinforcingthe wall thereof and tool joints such as at l2 and IT. This result ispossible only so long as the wall of the drill pipe H ismore flexiblethan the threaded portions of the pipe and tool joint connectingelements.

A very small amount of free space between the weighting sleeve and drillpipe may be used and the desired flexibility of the drill pipemaintained by employing a weighting sleeve having a spiral slot orgroove 21 which extends completely through the wall of the weightingsleeve. This slot provides for great flexibility in the weighting sleeveand avoids a rigid reinforcement to the drill pipe, even when unusuallysmall clearance between the drill pipe and weighting sleeve are used.The outer diameter of the sleeve 23 maybe of any convenient diameterdepending upon add to the drilling string, but is'preferably not suchfactors as the size of the drill bit employed and the weight per footwhich it is desired, to

substantially in excess of the outer diameter of the tool joints and mayadvantageously be of a smaller diameter than the tool joints. The latterconstruction is preferred since this provides for a shoulder at 29 .towhich-an elevator grip can "be conveniently attached and also can beused The pin and box elements are joined by a coarse threaded connectionH. A drilling bit I9 is threaded to the assembly on the lowerend'therefor attachment'of grappling tools in the event that there is abreak in the drilling string and a fishing job is'requiredi The sleeve23 preferably consists of a single section of tubing which extendssubstantially the entire distance between tool joints, sufilcien? spacebeing provided at one endb'etwcen the with the drill pipe by means ofengagement with an adjacent tool joint so that the sleeve is made torotate in unison with the drill pipe. This may be conveniently effectedby rigidly attaching the upper end of the sleeve to the adjacent tooljoint by welding as at 3|. Inasmuch as the principal function of thesleeve is to add weight without adding strength to the portion of thedrill pipe between tool joints, it is apparent that it is neithernecessary nor desirable to rigidly attach the sleeve at both ends totool joints. The weighting sleeve is preferably of slightly less lengththan the distance between tool joints as shown at 32. In order to obtainmaximum flexibility in the weighting sleeve, the helical slot 21preferably extends over substantially the entire length of the sleeve.In order to maintain a minimum number of pieces in the event of fractureof a sleeve and thereby simplify fishing jobs, the slot is preferablyterminated within a short distance of the upper and lower extremities ofthe weighting sleeve.

Any suitable number of weighting sleeves may be employed depending uponthe pressure with which it is desired that the bit bear upon theformation being drilled and upon the point in the drilling string atwhich it is desired to maintain the equilibrium between compression andtension forces. For example, if it is desired to maintain a givenequilibrium point and at the same time increase the load carried on thebit from 10,000 pounds to 20,000 pounds, a sufiicient number of sleevesare added to the lower end of pipe and being engaged with an adjacenttool the string to amount to 10,000 pounds additional weight. If 3 0. D.drill pipe and 5" O. D. tool joints are being used in the lower portionof the string, the weight will be about 16 pounds per foot. Sleeveshaving 3%" I. D. and 5" O. D. are mounted between the tool joints.

To illustrate by means of a particular example, a suitable weightingsleeve may be formed of 4 /2" 0. D. drill pipe. This pipe has aninternal diameter of 3.958" and therefore will fit loosely around adrill stem formed of drill pipe having an 0. D. of 3 In this case theannular space between the 3 0. D. drill stem and the weighting sleevewould be approximately 0.229". A slot may be conveniently cut in theweighting sleeve by means of an oxy-acetylene torch. This is preferablyof about in width. The vertical distance between turns of the spiral maybe varied between relatively wide limits, the preferred constructionbeing that which provides for maximum weight per. unit of lengthtogether with the desirable flexibility. In this particular example thevertical distance between turns is approximately 12'-' and the spiralslot terminates approximately 12" The sleeve may be conveniently markedfor cutting by simply wrapping a strip of paper 8" wide around thesleeve, leaving clearance between each turn of the paper.

nular clearance between the drill pipe and weighting sleeve is verysmall. By maintaining this clearance very small, a heavier walledweighting sleeve may be employed than is possible when usingconventional solid walled sections of weighting sleeve and this iseffected without exceeding the outside diameter of the tool joints orundesirably reinforcing the drill pipe.

The sleeves may be used in conjunction with or instead of conventionaldrill collars, although because of both structural and economicadvantages, the latter alternative is preferred. If conventional drillcollars are employed, the sleeves are usually positioned above andadjacent to the drill collars.

While a particular form of the invention has been described, it will beapparent to those skilled in the art that numerous modifications thereofmay be devised without departing from the spirit of the invention. IWhat is claimed is:

1. In a drilling string, the combination of sections of drill pipeconnected by tool joints of greater diameter than the drill pipe, aweight ing sleeve positioned on a lower portion of the.

string, said sleeve fitting loosely around the drill joint in suchmanner as to cause the sleeve to rotate with the string, said weightingsleeve hava ing a helical slot therethrough whereby the flexibility ofthe weighting sleeve is materially increased.

2. Apparatus in accordance with claim 1 in which the helical slotextends to within a short distance of each end of the sleeve. 3.Apparatus in accordance with claim 1 in which the upper end of thesleeve adjacent a tool joint is of sufilciently smaller outer diameterthan the tool joint to provide a shoulder for the attachment ofelevators.

4. Apparatus in accordance with claim 1 in which the outer diameter ofthe sleeve is of uniformly smaller outer diameter than that of adjacenttool joints.

5. In a drilling string the combination of sections of drill pipeconnected by tool joints of greater outer diameter than the drill pipe,a

weighting sleeve positioned on a lower portion of the string, the innerdiameter of the sleeve being 'less than" the outer diameter of adjacenttool joints, the sleeve fitting loosely around the drill pipe and havingan end thereof rigidly affixed to an adjacent tool joint, said weightingsleeve having a helical slot therethrough extending over a from the endsof the sleeve.

Weighting sleeves which are attached to drill:

major proportion of the length of the sleeve.

6. In a drilling string, the combination of sections of drill pipeconnected by tool joints of greater outer diameter than the drill pipe,a'

weighting sleeve positioned on the lower portion of the string betweentool joints, the outer diameter of the sleeve being less than the outerdiameter of adjacent tool joints, said sleeve fitting loosely around thedrill pipe and being rigid: ly attached to an adjacent tool joint, saidsleeve having a helical slot therethrough extending from a pointadjacent one end of the sleeve to a point adjacent the other end of thesleeve.

7. Apparatus in accordance with claim 6 in which the weighting sleeve isrigidly attached at its upper end to a tool joint.

8. Apparatus in accordance with claim 6 in the weighting sleeve issufllciently less than the distance between adjacent tool Joints to fitloosely therebetween.

. 9. In a drilling string, the combination of sections of drill pipeconnected by tool joints and a weighting sleeve positioned on a lowerportion of the string, said sleeve having a larger inside diameter thanthe outside diameter of said pipe and having a helical slottherethrough.

.10. The combination in accordance with claim 9 in which the upper endof the sleeve is rigidly fastened to the drill string and the lower endof 11. In a drilling string, the combination of sections of drill pipeconnected by tool joints and a weighting sleeve of larger insidediameter than said drill pipe positioned on a lower portion'of thestring between adjacent tool joints, said sleeve being in the form of aplurality of helices with one end of said sleeve engaging the drillstring in such manner as to cause the sleeve to rotate in unison withsaid string and the other the sleeve is free and spaced from itsadjacent 10 end oi the sleeve being free.

tool joint.

CHARLES F. TERRELL, JR.

